"The Americans are showing some external activity, we are working professionally through a special channel designed for this," Russian Deputy Foreign Minister Sergei Ryabkov was quoted as saying on Friday by Interfax.

"It is undeniable that Viktor Bout is among those who are being discussed, and we certainly count on a positive result," Ryabkov said.

Variously dubbed "the merchant of death" and "the sanctions buster" for his ability to get around arms embargoes, Bout was one of the world's most wanted men prior to his 2008 arrest on multiple charges related to arms trafficking.

For almost two decades, Bout was one of the world's most notorious arms dealers, selling weaponry to rogue states, rebel groups and murderous warlords in Africa, Asia and South America.

(Reporting by Guy Faulconbridge)